AM21GS400

iTrader: (2)

What's the easiest way to reach 300whp in a 00' gs400 without having to go turbo or superchager, I already have a K&N fipk and soon getting a cat back exhaust... what else do I need?

NEbiker10

iTrader: (1)

Apexi Neo will give you some more power, That along with headers will get you around 290-300whp.

I wish there was a decent OBDII tuner for these but that will never happen.

Hoovey689

iTrader: (16)

I would imagine headers make a big difference in adding rwhp

jriggs

75 shot of wet nitrous should put you up there.

sakataj

iTrader: (182)

except that nitrous is still forced induction and allthough he didnt specifically mention it in his first post, the thread title says without forced induction. if he wants to make 300hp he better break out the wallet...

ask rock who seems to have the highest hp NA v8 on the 2nd gen side and he still is at 289 i think with headers,intake,exhaust, plugs and i forget what else.... i think cams would send rock over 300 but they not worth it monetarily for the gs's...i priced a fully built head, cheaper for me to pull the gs and do the LS swap i been thinking bout for awhile now

Rock-a-Lex

iTrader: (4)

Brian is correct...but, eventhough it doesnt add power I would suggest both a more aggressive read end and a high stall TC. If you make around 280 - 290 whp, these two mods would make the car react like it has 20 more whp. Also, it depends how far you want to go. You can get a Meth injection kit such as from Snow Performance that is much more mild than nitrous but will def add another 30+whp. An n/a 300whp GS4 is def doable. IMHO, our tranny is the MAIN MAIN MAIN culprit. I would LOVE to see some one with a lot of bolt ons like myself drop in a supra 6mt tranny. I bet the car would be so much faster and more efficient resulting in more whp just by that. If I didnt buy an SC kit I would go this route...it is also pretty expensive though. But I NEVER seen anyone from cl with a custom 6mt tranny in a na GS4...that would be awesome!

SSxblazer

Headers, intake, tune, port heads, exhaust, mild cam, 3200 stall, ported intake mani, ported tb......


Or just stock with a 75 shot.....


Btw, don't waste your time on meth injection on NA.....YES it will give gains, but for the 1k or so that you end up spending on the kit and install and such (vs 300-400 for a Zex 75 shot kit).......its just a waste of money.

Rock-a-Lex

iTrader: (4)

Ok, I agree but look at ported heads, ported intake manifold, ported heads...all would cost more than $1000 bucks so you may as well run nitrous. But I agree, if one is looking for strictly an na car imho I would leave out the notion of nitrous or meth injection.

eyecon7

iTrader: (2)

What's the compression ratio on the 400?

justablkv8

iTrader: (2)

our compression ratio is like 50,000:1

sakataj

iTrader: (182)

it would be awesome but pointless on a NA motor especially for 300 hp...btw rock u ever gonna actually install that SC?

with even a mild cam i would recommend springs/retainers and with tall this stuff i PROMISE your in about 8k especially if you arent doing the labor yourself and its just not worth it to make 300 hp.....for that money pull the motor and a add a LS1/2 with the better flowing heads/intake and you can make 350 for easily under that

a better OEM idea might be using the gs400 block which is stronger (thicker rods/yada/yada) with the better flowing GS430 heads and see what kind of power you make

the actual compression ratio is 10.5:1

vwynn

iTrader: (4)

at 300 whp our tranny will handle that quite well. i mean us FI GS400 guys are pushing more than 300. some one stock trannys.

vwynn

iTrader: (4)

i wouldnt say pointless. Having a 6speed would grealty improve the acceleration of the car also making it feel faster. Our OEM trannys are slow and a manual would be

sakataj

iTrader: (182)

for the 5-7k it will cost for the transmission/conversion it is incredibly stupid on a NA motor making 300hp, now if you make 600-800+ i would def say go for it.... remember you could always build your tranny not to mention you loose less boost "in between shifts" on a automatic compared to a manual. although i miss owning a manual alot the cost factor outweighs the means for me...

bigwes

some good ideas that i have been reading. im looking to get my GS4 to about 350hp to the crank. wouldnt headers, intake, exhaust, and maybe a apexi neo tune get me there?? im not looking for a ton of extra power, but just a little umph.